Natural fibers, with the exception of silk which is continuous in filament, are composed of relatively short fibers. Cotton averages about 1 inch staple length, wool about 3-4 inches and linen strand may be 12 to 20 inches or more. Synthetic fibers, on the other hand, are produced in continuous filaments which can be, and generally are, miles long. About 1920, interest was first taken in the production of synthetic fibers in lengths comparable to those of cotton and wool fibers, in order to spin such fibers on the cotton or worsted system.
For the manufacture of staple fiber much the same methods and materials for ordinary continuous filament fibers can be used. For example, as the filaments are extruded from the spinnerets, which may each have 1000 or more orifices, they are brought together in the form of a bundle or tow. The tow is converted to staple fiber by one of three general cutting methods; wet cutting, dry cutting, or continuous process. The first two methods result in bundles of fibers, pointing in all directions, which are baled; the third method retains the parallel arrangement of the filaments. These cutting methods have the disadvantage that frequent resharpening of the cutter knives is required.
What is desired is a method for producing short fiber lengths without resorting to cutting the fiber.
Accordingly it is an object of the present invention to provide a method for producing short fiber lengths.
Other objects, aspects and advantages of the present invention will become apparent to those skilled in the art from a reading of the following disclosure, the attached drawing and the appended claims.